Windows 11 Snipping Tool OCR (OneOCR)

Offline OCR engine extracted from the Windows 11 Snipping Tool, with full-featured C++ CLI, reusable DLL wrapper, and Python visualization.

Based on: https://b1tg.github.io/post/win11-oneocr/

DeepSeek Harness plugin

This repository can be installed as a DeepSeek Harness plugin:

dsh plugin add github:hawkhai/win11-oneocr

It registers oneocr_recognize, a model-facing tool that accepts a local image path and returns recognized text together with OneOCR's structured line/word polygons, confidence values, image angle, and handwriting style. The tool runs locally on Windows 11; image bytes are not sent to an external OCR service.

The bundle defaults to the prebuilt bin/ocr.exe and its adjacent runtime files. Override ocrBin, timeoutMs, or maxOutputBytes in the plugin row if needed.

Features

Prerequisites

• Windows 11 (tested on 23H2+)
• Snipping Tool 11.2409.25.0+

Copy these 3 files from the Snipping Tool installation folder into the same directory as ocr.exe:

• oneocr.dll
• oneocr.onemodel
• onnxruntime.dll

Find the Snipping Tool folder:

Get-AppxPackage Microsoft.ScreenSketch | Select-Object -ExpandProperty InstallLocation

Example: C:\Program Files\WindowsApps\Microsoft.ScreenSketch_11.2409.25.0_x64__8wekyb3d8bbwe\SnippingTool

CLI Usage (ocr.exe)

ocr.exe <image1.png> [image2.jpg ...] [options]

Options

Examples

# Single image → JSON
ocr.exe screenshot.png

# Plain text output (pipe to file)
ocr.exe screenshot.png --text > result.txt

# Batch process
ocr.exe img1.png img2.jpg img3.bmp

# Custom options
ocr.exe photo.jpg --max-lines 50 --resize 800x600 -o result.json

JSON Output Format

{
  "file": "test.png",
  "image": { "width": 771, "height": 479, "step": 3084 },
  "image_angle": 0.0643,
  "line_count": 2,
  "lines": [
    {
      "index": 0,
      "text": "Hello World",
      "bounding_box": [
        13.0, 38.0, 458.0, 38.0,
        458.0, 77.0, 13.0, 76.0
      ],
      "style": { "type": "printed", "confidence": 0.035 },
      "word_count": 2,
      "words": [
        {
          "index": 0,
          "text": "Hello",
          "bounding_box": [
            14.35, 39.70, 140.35, 41.31,
            139.93, 73.42, 13.78, 74.09
          ],
          "confidence": 0.987
        }
      ]
    }
  ]
}

DLL Wrapper (oneocr_wrapper.dll)

A reusable C DLL wrapper with 3 main APIs:

C++ Header-Only Usage (oneocr.h)

#include "oneocr.h"

OneOcr ocr;                               // loads oneocr_wrapper.dll
ocr.initModel(L".");                      // directory with oneocr.dll + .onemodel

std::string json;
ocr.ocrImage(L"test.png", json);          // basic OCR
ocr.ocrImageEx(L"test.png", json, 50);    // max 50 lines
ocr.ocrImageRaw(bgra_ptr, w, h, json);    // raw buffer OCR

Visualization (visualize.py)

python visualize.py <image_path> <json_path> [output_path]

Features:

• 8-point polygon bounding boxes (lines in red, words colored by confidence)
• Confidence score labels below each word
• Handwritten lines highlighted in orange, printed in red
• Image angle and line count overlay

Build

Requires: MSVC (Visual Studio), json.hpp (nlohmann/json), stb_image.h.

# Build CLI
cl /EHsc /O2 ocr.cpp /Fe:ocr.exe

# Build wrapper DLL
cl /EHsc /O2 /LD oneocr_wrapper.cpp /Fe:oneocr_wrapper.dll

# Build test
cl /EHsc /O2 oneocr_test.cpp /Fe:oneocr_test.exe

Other Implementations

Credits

• b1tg - Original reverse engineering and C++ implementation
• AuroraWright/oneocr - Python package with web server
• wangfu91/oneocr-rs - Rust binding with full feature coverage
• Cecilia-pj/win11_oneocr_py - Original Python port

License

MIT